A Virtual Manufacturing (VM) host and migration thereof drives the development of the large-scale layer-2 network of the data center. With the expansion of the network scale, the number of network devices is growing, and the network management becomes a thorny issue in data center infrastructure management. At the same time, the modern large data center puts forward high requirements on port density which the network provides for the server, for example, the scale of ten thousand servers has been a common requirement in Internet data center. Port extension technology is one way of improving port density that has received industry recognition.